A wide variety of products are packaged in metal containers. Metal containers are desirable because they are durable and provide a distinctive appearance. Metal containers further can be formed in various shapes and sizes, and decorated with artwork. As a result, metal containers are often used to hold consumer products.
It is important that a metal container adequately retain the product it holds. Many products have a low viscosity, and therefore flow easily through cracks or seams in packaging. For example, products such as lotions, creams, and wax candles are heated during manufacture to obtain a flowable material which is processed and packaged more easily. Furthermore, products such as candles experience elevated temperatures when used for their intended purpose by the consumer, and therefore again create a flowable material. Metal containers used to hold those products must therefore be capable of retaining material having low viscosity.
Previously, glass jars and drawn metal containers have been used to hold easily flowable materials. Those conventional containers are typically formed as single, unitary pieces so that no seams are formed through which the material may leak. Production of these previous containers in varied shapes and sizes requires extensive machine retooling and therefore is overly time consuming and expensive. Furthermore, it is difficult to improve the appearance of these containers with artwork. Relatively deep drawn metal containers, for example, require artwork to be applied to a flat blank in distorted form so that, after the container is drawn into shape, the artwork is bent into the proper visual appearance. Layout and application of distorted artwork is, however, overly difficult and expensive.
Metal containers formed from multiple pieces are known which are less expensive to make in different shapes and sizes and easier to decorate. For example, a standard three-piece metal container has a base and side wall joined together to form the container, and a removable cover. The side wall is formed from a flat strip of metal that is then bent or rolled into a cylinder, square, or other shape, either regular or irregular. The ends of the side wall are joined to complete the shape. The base is generally flat and is formed to fit on a bottom edge of the side wall. Finally, the cover is a separate piece that is sized to removably fit over the top edge of the side wall.
Unfortunately, multiple piece metal containers create an increased risk of product leakage. From the above, it will be evident that a number of seams are formed between the different components of the three-piece metal container. A seam is formed at the side wall along the vertical height of the container where the opposite ends of the metal strip are joined. In addition, a seam is formed around the entire periphery of the side wall where it joins the base. As a result, materials having low viscosity may leak through the seams of the container.
Previous candle containers have employed various approaches to prevent leakage through container seams. Some containers, for example, have carefully formed seams which are tightly folded. The tight seams, however, are difficult to form and do not reliably prevent leakage. Other containers have used volatile or hazardous materials (such as methyl ethyl ketone(MEK)-based materials) to seal the container seams, and therefore pose a threat to the environment. Furthermore, these materials are typically applied to the container by hand (or "hand-doped") and therefore require expensive manual labor.